Every when in a while, you’ll hear a wizened veteran the our sport waxing eloquent around the ‘good ol’ days’ of hill biking, when wheels were tiny and brakes to be actuated by cables. “Sure, castle didn’t prevent you that well“, she’ll say, with a faraway look in her eye, “But that was component of the challenge!“. When vintage bikes might be regaining some of their former popularity among the ironic-mustached crowd, the industry-wide adoption of hydraulic-fluid activate brakes has allowed our sports to progress to the point it’s at today… through the majority of riders capable of stopping before slamming right into trailside obstacles.

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1994 XC human being Champs. Have the right to we every take a 2nd to be thankful this is no longer the norm?

If you’re the proud owner of a cycle equipped with hydraulic actuated disc brakes, congratulations. If you’ve ever before looked at those brakes and also wondered what go on within them, then this post is because that you!

Let’s start with the basics: how hydraulic disc brakes work. Broken down as simply as possible, when you pull the brake bar of a hydraulic brake, the lever blade depresses a piston inside the bar body, which pressures hydraulic fluid through the brake heat to the caliper, whereby it forces two an ext pistons together, compressing the brake pads versus the rotor.


Hydraulic disc brakes are generally an ext powerful than mechanical (cable actuated) disc brakes, as the hydraulic liquid does not compress under pack (transferring every one of your squeezing power directly to the brake pads), and also this fluid actuates two pistons, fairly than one. With an ext power comes much more control, and with much more control comes an ext fun on your bike.

As with any type of advancement, there are some things that one loses when relocating to hydraulic disc brakes (the consistent fear of crashing into stationary objects being one). Hydraulic disc brakes require an ext maintenance than mechanical brakes, due to the intrusion of waiting (which does compress) right into your brake fluid (which doesn’t). Hydraulic brakes are likewise more daunting to install onto internally-routed frames, together they call for bleeding (of the brake system, not the installer) when the line is cut. If girlfriend live in fear of performing maintain on your bike, and also your nearest LTP sporting activities dealer is a parsec away, a brake prefer the TRP Hy/Rd can be a better bet because that you, as its semi-mechanical design cuts under on the require for regular maintenance.

The TRP HY/RD semi-mechanical key brake blends cable and hydraulic technologies for less complicated installation and also lower maintenance.

So, assuming that you’re persuaded that friend made the appropriate decision in going hydraulic, right here are some valuable things come know.

With an excellent power, comes good modulation

As we discussed, hydraulic fluid doesn’t compress favor air, water, or brake cables. This method that friend don’t suffer any loss the power in between you pulling the brake lever and also the pistons clamping down on the rotor. Yet as we all know from watching ‘fail’ videos of people flying over the handlebars of their bikes, too lot power overall isn’t ideal. Modern disc brakes are designed to permit modulation- the capacity to finely control how much strength is exerted- to keep you native locking your brakes up every time.

Modulation isn’t because that everyone, however. Part riders, myself included, prefer brakes to be an ext touchy, and also to provide the whole of the braking strength as quickly as possible. Brake systems like TRP’s G-Spec DH and also Trail tend to have much more of an on/off feeling (more power, less modulation) than brakes choose SRAM’s code or overview brakes.

Not all hydraulic fluids are produced equal

There space two different varieties of hydraulic fluid used in bike disc brakes; dot fluid and also Mineral oil. DOT fluid is the standard hydraulic fluid used in brakes, and also mineral oil is exactly what you think that is- very similar to the stuff you’d buy at the pharmacy. Both fluids room incompressible and resistant to heat, making them best for use in brake systems. However, that’s around where the similarity end, and also it have to be noted that mineral oil and DOT liquid systems are NOT COMPATIBLE. (You can’t adjust the hydraulic liquid in one system for another.) that said, you have the right to use this details to notify your decision around what kind of brakes come buy, and also it can additionally guide your acquisition of aftermarket hydraulic fluids for once you do should bleed her brakes. To break down the differences in between the two systems, let’s look in ~ some elements of brake fluid.


Your brakes will be clearly marked with the liquid that they’re draft for.

Boiling Point: Brakes create a many heat, specifically on long downhill sections. Once a liquid gets too warm it transforms from an incompressible fluid to a compressible gas, and also braking power suffers accordingly. The boiling points of the different DOT fluids and mineral oils vary significantly, so it’s a an excellent idea to save these in psychic when picking your following brake system. The boiling suggest of dot fluids relies on even if it is the liquid is brand brand-new (dry) or even if it is it has actually been exposed come water (wet), i m sorry is why two boiling suggest numbers are regularly given. (Mineral oil doesn’t absorb water, so only the dried boiling suggest applies.) Maxima DOT fluid has a an especially high boiling allude due to its general awesomeness. If friend want far better braking performance from your dot brakes, operation Maxima brake fluid.


Water solubility: on a long enough timeline, water will get into your brake system. Water is incompressible, as with brake fluid, yet its much reduced boiling point way that your brake performance can suffer as quickly as the brakes heat up. Water gets into the brake system through microscopic pores in brake lines, past seals and also through seams in the caliper and lever bodies. DOT liquid will absorb water over time, up to 3% over the food of 2 years, providing them a spongy feeling under heavy use. When mineral oil is hydrophobic (won’t absorb water), the water the does acquire into the device tends come amass near the brake caliper (the lowest point in the line), whereby it heats up quickly and can cause even much more sudden brake fade. The takeaway here is that you must bleed your brakes when a year, no matter what kind of fluid they use.

Popularity: Both dot fluid and also mineral oil are widely available, yet DOT’s use in the automotive people guarantee easier access and lower prices. When the mineral oil you can pick up in ~ the pharmacy could seem favor a good idea, save in psychic that, unlike period fluid, mineral oil is not federal government regulated, for this reason non-bike-specific assets likely won’t perform virtually as well. TRP’s Mineral oil is a great way to choose up a whole lot that high-quality bike-specific mineral oil at a kind price.


Mineral oil is non-corrosive, so friend don’t need a ton of safety gear to work on it. (though eye defense is tho recommended).

Shelf Life: DOT fluid absorbs water end time, where mineral oil does not. Thus, an open bottle the DOT liquid will last around 2 years before it have to be thrown out, but a bottle of mineral oil is an excellent for years.

The need to bleed.

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Any hydraulic brake mechanism will require bleeding once a year to remove air, water, and contaminants trapped in the system. Bleeding entails forcing brand-new fluid right into the system, and also removing the old contaminated fluid, without allowing air to go into the system. The easiest means to perform a brake bleed is to take your bike to your neighborhood LTP sports dealer and let them execute it. The 2nd easiest way is to acquisition a bleed kit and try it yourself! keeping watching this room for an instructional video.


Two that the finest brakes in MTB – TRP’s Mineral Oil G Spec DH and SRAM’s DOT fluid CODE RSC

So over there you have actually it; as much information as you’ve ever before wanted around hydraulic brake systems. If you have further questions, girlfriend can always message us on society media, or head into your neighborhood Live come Play sporting activities dealer for the lowdown indigenous their knowledgeable mechanics!